Project Summary Our long-term goal is to better understand how neighborhood environments determine health trajectories across the lifespan of different societies. With rapid population aging, cognitive impairment and dementias have become major health and social problems worldwide, causing loss of independence in daily activities and lowering quality of life in old age. Previous research has demonstrated an association between neighborhood environments and cognitive function in middle-aged and older adults. However, it is not well understood how neighborhood context contributes to cognitive function. The primary objective for the proposed research is to determine the underlying mechanisms and potential moderating factors in the relationship between neighborhood environments and cognitive function and cognitive decline in middle and old age in a developing country. China is being targeted as a developing country that is experiencing rapid population aging, which has resulted in rising prevalence of Alzheimer?s disease and related dementias. The country is also experiencing both a decline in families as the major source of eldercare and a lack of long term care facilities. Further, specific cultural, social, and economic context factors in China that warrant attention when considering the influence of neighborhood environments on health in aging adults will provide a rich landscape for identifying mechanisms and factors that may generalize across cultures. The project has three specific aims: (1) to identify the mechanisms of the effects of neighborhood environments on cognitive decline among middle-aged and older Chinese adults; (2) to determine whether the effects of neighborhood environments on cognitive decline vary by gender, urban/rural residency, and age cohort; and (3) to determine whether neighborhood environments have different effects on different domains of cognition. This project will analyze data from three waves of the China Health and Retirement Longitudinal Study (CHARLS) and other sources. It will measure neighborhood natural, built and social environments using CHARLS?s community survey and other sources and examine their separate and joint effects on cognitive decline. A series of multi-level linear growth curve models will be estimated to identify the mechanisms in the relationship between neighborhood environments and cognitive decline and examine whether this relationship varies by gender, urban/rural residence, age cohort and different domains of cognition. This approach is innovative because it shifts the focus from the establishment of an association between neighborhood environments and cognition to the identification of mechanisms and contexts in this relationship. The proposed research is significant because it can advance our understanding of the specific pathways between neighborhood environments and health in later life. With rapid population aging and overburdened medical care systems worldwide, identifying the mechanisms through which neighborhood environments affect the health trajectories of older people might suggest more effective forms of interventions.